linux-kernel - Re: [PATCH 2/4] ext4: remove unnecessary check from alloc_flex

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Message-ID: <20231019112434.epx7cl7okturn4xq@quack3>
Date:   Thu, 19 Oct 2023 13:24:34 +0200
From:   Jan Kara <jack@...e.cz>
To:     Baokun Li <libaokun1@...wei.com>
Cc:     linux-ext4@...r.kernel.org, tytso@....edu,
        adilger.kernel@...ger.ca, jack@...e.cz, ritesh.list@...il.com,
        linux-kernel@...r.kernel.org, yi.zhang@...wei.com,
        yangerkun@...wei.com, yukuai3@...wei.com
Subject: Re: [PATCH 2/4] ext4: remove unnecessary check from alloc_flex_gd()

On Wed 18-10-23 19:42:19, Baokun Li wrote:
> In commit 967ac8af4475 ("ext4: fix potential integer overflow in
> alloc_flex_gd()"), an overflow check is added to alloc_flex_gd() to
> prevent the allocated memory from being smaller than expected due to
> the overflow. However, after kmalloc() is replaced with kmalloc_array()
> in commit 6da2ec56059c ("treewide: kmalloc() -> kmalloc_array()"), the
> kmalloc_array() function has an overflow check, so the above problem
> will not occur. Therefore, the extra check is removed.
> 
> Signed-off-by: Baokun Li <libaokun1@...wei.com>

Looks good. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  fs/ext4/resize.c | 3 ---
>  1 file changed, 3 deletions(-)
> 
> diff --git a/fs/ext4/resize.c b/fs/ext4/resize.c
> index c6d4539d4c1f..0a57b199883c 100644
> --- a/fs/ext4/resize.c
> +++ b/fs/ext4/resize.c
> @@ -236,10 +236,7 @@ static struct ext4_new_flex_group_data *alloc_flex_gd(unsigned int flexbg_size)
>  	if (flex_gd == NULL)
>  		goto out3;
>  
> -	if (flexbg_size >= UINT_MAX / sizeof(struct ext4_new_group_data))
> -		goto out2;
>  	flex_gd->count = flexbg_size;
> -
>  	flex_gd->groups = kmalloc_array(flexbg_size,
>  					sizeof(struct ext4_new_group_data),
>  					GFP_NOFS);
> -- 
> 2.31.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR